Dry fractionation of corn

ABSTRACT

Novel grain processing methods and the products obtained therefrom are disclosed. Methods may include separation of pericarp fractions, hydrolysis of the pericarp fractions one or more time, and fractionation of the hydrolyzed pericarp fractions. Hydrolyzed pericarp fractions have applications including fermentation media, livestock feed, and fuel feedstocks.

CLAIM FOR PRIORITY

This application claims priority to pending U.S. Provisional PatentApplication No. 60/961,875, filed on Jul. 25, 2007. That application isincorporated by reference as if fully rewritten herein.

STATEMENT OF FEDERALLY SPONSORED RESEARCH

This invention was made with the assistance of United States Departmentof Agriculture Grant NRCS 68-3A75-3-140 “Biomass research andDevelopment for the Production of Fuels, Chemicals, and Improved CattleFeed.” The United States government may have some rights to thisinvention.

BACKGROUND OF THE INVENTION

The following includes information that may be useful in understandingthe present teachings. It is not an admission that any of theinformation provided herein is prior art, or material, to the presentlydescribed or claimed subject matter, or that any publication or documentthat is specifically or implicitly referenced is prior art.

1. Field of the Invention

The present teachings relate to, but are not limited to, the field ofcorn product production. Embodiments relate, for example, to methods forproduction of ethanol and stillage.

2. Background of the Art

Corn processing methods may be divided into a number of broad groups,including dry grind ethanol, modified dry grind ethanol, corn wetmilling and corn dry milling. (Singh, V., et al., “Modified Dry GrindEthanol Process,” Publication of the Agricultural Engineering Dept. ofUniv. of Ill. and Urbana-Champaign, UILU No. 2001-7021, Jul. 18, 2001,incorporated by reference herein). Variation within processes may occurbased on the preferences of the miller.

In a typical traditional dry grind ethanol operation, whole corn isground, mixed with water, treated with alpha-amylase enzyme, and cooked.The resulting “mash” is treated with glucoamylase enzyme to convert itto glucose. The converted mash is fermented and distilled, producingethanol, distillers dried grains with solubles (DDGS) and carbondioxide.

Traditional dry grind ethanol operations have a number of disadvantages.For instance, use of the entire kernel in the mash, including thenon-starch portions of the kernel, reduces the efficiency of theoperation. Furthermore, the non-ethanol byproducts (including DDG) havea relatively low value, and they include a high oil content that isrelatively difficult to extract.

In a proposed modified corn dry grind ethanol operation, corn is firstcleaned in a dry state to remove cobs and other undesirable componentssuch as metal or stones. The corn may also be wet-cleaned to remove dirtor dust. Following cleaning, the corn is tempered to between about 14%and 22% moisture, typically about 20% moisture. Tempering entailstreating the corn with cold water, hot water, and/or steam. This softensthe pericarp and causes the germ to become rubbery, which allows thosecomponents to be more easily separated from the endosperm.

Following tempering, and while the corn is still moist, the corn ismilled to separate portions of the germ, tip cap, and pericarp (bran)from the endosperm, which is customarily used to make grits, meals, andflours. The pericarp and germ proceed through the “through stock”stream, which is dried, cooked, and aspirated. This removes thepericarp, which is dried and used as an animal feedstock. The remainingdried germ, which typically contains about 45% corn oil on a dry basis,is transferred to a separate facility, where the oil is removed throughchemical extraction and/or auger press/expeller. The corn residue fromthe press or extractor is then used as an animal feed.

The non-pericarp, non-germ components of the kernel are ground andconverted to mash, as is done in the conventional dry grind ethanoloperation. The mash is treated with enzymes to convert it to glucose.The glucose is fermented and distilled, producing ethanol, an animalfeed, and carbon dioxide. The animal feed would include yeast cell mass,fermentation by-products, and any other unfermented solids.

Others have attempted to modify the dry grind process to providehigher-value products with varying levels of success. For example,Singh, V., et al., Cereal Chemistry, 73(6): 716-720 (1996), U.S. Pat.No. 6,254,914, to Singh, et al. (“Singh II”), and U.S. Pat. No.6,899,910, to Singh, et al. (“Singh III”) report removal of germ fromsoaked corn. The processes include a long tempering phase, and theentirety of each Singh process is performed in the aqueous phase. Singhand Singh II further require addition of substances to the aqueous phaseto allow the germ to float and to enable separation by skimming orhydroclone. Singh III reports use of enzymatic hydrolysis of corn starchto increase the density of the aqueous phase and allow separation of thecomponents.

U.S. Pat. No. 6,592,921, to Taylor, et al. reports fractionation ofpericarp from corn through addition of ammonia gas to the corn. Taylor,et al. does not teach or suggest the use of water in lieu of ammonia,and it does not teach germ fractionation. U.S. Patent Application No.US20070037267A1, to Lewis, et al. reports corn fractionation to producea starch-rich stream, though no fractionation is actually described andethanol is only purportedly produced from residual starch.

U.S. Pat. No. 4,181,748, to Chwalek, et al. reports a dry corn millingprocess purportedly including use of residual starch in furtherwet-milling. U.S. Pat. No. 6,962,722, to Dawley, et al., and U.S.Published Application No. US20060057251, to Dawley, et al. reportproduction of a high-protein or mid-protein distillers' dried grain(DDG).

International Patent Publication No. WO2007/015741, to Jansen, et al.and U.S. Pat. No. 6,982,328, to Werpy, et al., report a wet millingprocess including recovery of starch from fiber. International PatentPublication No. WO 2006/055489, to Beaver, et al., reports separation ofcorn into a lower starch fraction and a higher starch fraction.

BRIEF SUMMARY

Generally, various embodiments of the invention provide methods fortreatment of grain and grain products to obtain higher value streamsfrom those products in a dry milling operation, exemplified herein by acorn dry milling operation. Embodiments provide new, more cost-effectiveways of processing grains prior to fermentation. Typical embodimentsprovide effective removal of pericarp and separation of germ prior togrinding and saccharifying the endosperm fraction for use infermentation, resulting in a substantial energy savings. For exampleremoving the non-fermentables from the fermentation could lead to anenergy savings of up to 2,800 BTU/liter ethanol produced. Furtherembodiments include processing of the pericarp fraction bythermochemical hydrolysis and fractionation. This further processing maycreate product streams with enhanced value and/or utility. In aparticularly advantageous embodiment, the hydrolyzed pericarp fraction,which contains solubilized xylose, is added along with the saccharifiedstarch fraction to the fermentation medium thereby increasing the yieldof ethanol from the fermentation.

One aspect of the present disclosure is a modified process for ethanolproduction from a grain in a dry-grind grain processing plant. Theprocess includes separating a pericarp enriched fraction from germ andendosperm enriched fractions of a ground grain, hydrolyzing celluloseand hemicellulose from the separated pericarp fraction to form a xyloseenriched soluble fraction, and adding the xylose enriched solublefraction to a fermentation medium that includes conventional hydrolyzedstarch from the endosperm enriched fraction of the grain to produceethanol. This process of extracting sugars from the otherwiseunfermentable pericarp tissue increases the ethanol yield per bushel ofgrain by as much as 0.3 gallons per bushel.

In a typical practice, hydrolyzing the cellulose and hemicellulose fromthe pericarp includes thermochemically treating the separated pericarpfraction by exposure to a temperature greater than 25° C. in thepresence of at least one of a mineral acid, an organic acid, a mineralbase, and an oxidizing agent. Optionally, the hydrolyzing furtherincludes treating the separated pericarp fraction to at least one of acellulose and a hemicellulose degrading enzyme.

Another aspect involves new methods for separating the pericarp fractionfrom the endosperm fraction of the grain in a manner that simultaneouslyproduces a better endosperm fraction as a source of the hydrolyzedstarch and a better pericarp fraction for solubilization of thecellulose and hemicellulose. In a advantageous embodiment, the pericarpenriched fraction is obtained by aspirating the ground grain by upwardflow of gas at a first air pressure in a hopper and harvesting a firstfraction of lighter components that are enriched toward an upper portionof the hopper, which are separated from a first fraction of heaviercomponents that are enriched in a lower portion of the hopper. Thelighter components are enriched with pericarp while the heaviercomponents are enriched with germ and grain. In a further enhancement,after harvesting the lighter components, the aspirating gas is increasedto a second air pressure greater than the first air pressure to separatethe first fraction of heavier components into a second lighter fractionenriched with endosperm and a second heavier fraction enriched withgerm, which can be harvested separately. The endosperm enriched fractionis liquefied and treated with a starch hydrolyzing agent(saccharification) to provide the hydrolyzed starch which is the primarycarbohydrate source for the fermentation medium. This process not onlyprovides an economical way to clean the endosperm, but also provides amore economical way to obtain a relatively clean germ fraction, whichcan be extracted to obtain oil.

In yet another aspect, the method provides for a way to extract furthervalue from the pericarp fraction. In a conventional dry grind ethanoloperation, pericarp containing material from a dry grind ethanol plantis included with the whole grain, or germ extracted grain in thefermentation medium and harvested as distillers dried grains (DDGs) postfermentation. DDGs are typically used as feed supplements for animals.However, pericarp tissue that has been hydrolyzed to yield solublexylose containing material which is then used for the fermentation hasless value as a feed. In certain embodiments of the present teaching thenon-soluble pericarp material obtained after hydrolysis and removal ofthe xylose containing soluble fraction, is further treated by at leastone process selected from pyrolysis and hydrothermal upgrading. Theproduct of such pyrolysis or hydrothermal upgrading is a crude oil likesubstance (i.e., a “biocrude”), that can be used as starting materialfor further fractionation to make a fuel or fuel additive or useddirectly as a crude fuel material.

One exemplary embodiment of a process disclosed herein is, in a drygrind grain processing plant, tempering a dry weight of grain by addingabout 10% wt of water per dry weight of grain and heating to atemperature of about 20-40° C. for a period sufficient to swell a germcomponent of the grain; grinding the tempered grain; separating theground grain by aspiration to obtain a first fraction enriched withpericarp and a first amount of starch fines and a second fractionenriched with endosperm and germ; separating the first fraction bysizing to form a pericarp enriched fraction and a fines enrichedfraction; separating the second fraction into an endosperm enrichedfraction and a germ enriched fraction; adding water and a hydrolyticagent to the pericarp enriched fraction to form a first mixture andheating the first mixture for a time and temperature sufficient tohydrolyze at least 45% of the fiber in the pericarp into a soluble sugarfraction containing xylose. The soluble sugar fraction containing xyloseis then used to supplement the fermentation medium.

The methods provided herein increase the yield of ethanol per bushel ofcorn to between about 2.7 to about 3.0 gallons per bushel in comparisonto a yield of about 2.4 to 2.7 gallons by conventional dry grindfermentation.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a conventional dry mill ethanol production process.(Singh, et al.).

FIG. 2 depicts a modified dry mill ethanol production process. (Singh,et al.).

FIG. 3 depicts a flow chart of a dry mill ethanol production processaccording to one embodiment of the invention.

FIG. 4 depicts a flow diagram of a modified dry milling process.

FIG. 5 depicts a flow diagram of a modified dry milling processaccording to an embodiment of the invention.

FIG. 6 depicts a dry mill ethanol production process of a furtherembodiment of the invention, as reported in Example 3, below.

FIG. 7 depicts a flow chart of an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present teaching describes several different features and aspects ofthe invention with reference to various exemplary embodiments. It isunderstood, however, that the invention embraces numerous alternativeembodiments, which may be accomplished by combining any of the differentfeatures and aspects described herein in any combination that one ofordinary skill in the art would find useful.

Processing methods as described herein may offer many advantages overthe prior art. Of course, the scope of the invention is defined by theclaims, and whether an embodiment is within that scope should not belimited by whether the method provides one or more of these advantages.Processing methods may require lower energy input, lower capital costs,and lower processing costs than other methods known in the art. Minimalwater input may be required. Processing according to embodimentspresented herein may be particularly advantageous for ethanolprocessing; for example, processes provided herein may increase ethanolproduced per bushel of corn from about 2.7 gallons per bushel to between2.9 and 3.0 gallons per bushel. Hydrolyzed pericarp fiber may be used toprovide between about 7,000 and 17,000 BTU/bushel of corn if returned tothe boilers used to provide energy for the aspiration or relatedprocesses. Hydrolyzed pericarp produced by embodiments of the inventionmay also be used as fuel or a fuel precursor for a variety ofapplications, including but not limited to biodiesel, biooil, andsyngas.

A. Corn Processing

Discussion of the methods and compositions taught herein will be madeusing corn as an exemplary grain for the practice of the invention.Those skilled in the art will, with the benefit of this disclosure,recognize that although methods and compositions are described withrespect to corn (maize), the methods and compositions may be beneficialwhen practiced with other grains and grain-like substances. Grains orgrain-like raw materials for use with the teachings herein may include,for example, but are not limited to, wheat, millet, barley, sorghum,triticale, rice, corn, amaranth, buckwheat, rye, oats, and quinoa. Cornis preferred. No particular strain of corn is required.

Embodiments provide methods for processing corn in a dry milling ormodified dry milling process. One embodiment for providing ethanol andstillage includes the steps of tempering whole corn to soften and loosenthe germ and pericarp. Prior to tempering, the corn may be cleaned toremove rocks, dirt, or other undesired foreign matter. For tempering,water may be added at varying amounts by weight. Addition of 10% waterby weight of the corn is preferred, though in other embodiments theamount of added water is between about 5% and about 15% by weight of thecorn stream, and in other embodiments, the amount of added water isbetween 0 and 20%.

Following addition of water, the corn is held at 25° C., or between 20and 30° C., and continuously mixed for a period of time to complete thetempering. The temperature of the corn/water mixture is between 15 and35° C., preferably about 25° C. If heating the mixture is necessary, itis preferably done using steam. The time of mixing is 0 to 120 minutes,preferably 15-60 minutes. Mixing may be conducted by any mixer,including but not limited to ribbon mixer, auger, or blender.

Following tempering, the corn is ground or milled. In a separateembodiment, the corn can be ground or milled without tempering, however,tempering improves the separation of pericarp material as describedherein after. Milling may be done by any method. Preferred methodsinclude milling by Fitz mill or by Beall degerminator or Satakedegerminator. Milling and grinding produce a ground corn stream, whichis a heterogeneous mixture including germ, endosperm, pericarp, andfines. The fines are primarily starch, and the pericarp is primarilyfibrous material.

The ground corn stream is then separated to remove the oil-containinggerm and the starch/gluten endosperm from the pericarp and fines. In apreferred embodiment, the germ and endosperm are separated from thepericarp and fines by aspiration. The aspiration can be completed in aKice gas aspirator using a differential pressure of 0.5-1.0 inches ofwater. The heavy fraction contains the germ and endosperm grits, whilethe light fraction is a pericarp enriched fraction containing thepericarp and fines. Residence time in the aspirator is a function of theheight and width of the aspirator. Parameters such as flow rate andresidence time will depend on the height, width, and other physicaldimensions of the aspirator.

Following separation of the pericarp and fines from the germ andendosperm, the pericarp and fines are separated to provide a pericarpfraction and a fines fraction. In a typical embodiment the separation isperformed by sieving. This can be accomplished in a Sweco shakingscreener with a U.S. standard sieve size of 12. The −12 (through orunder 12) is part of the endosperm or starch fraction and the +12 (over12) is the pericarp fraction. Typically, the pericarp fraction at thisstage still contains about 15%-30% attached starch on a weight basis.After separation, the pericarp may be treated and used a variety ofways, as set forth in more detail in Section B, below.

Once separated from the pericarp and fines, the remaining germ andendosperm can be prepared for ethanol fermentation. There are severalpossible methods for this. One method is to aspirate the heavys(throughs) from the first aspiration operation at a higher differentialpressure. For example, at a differential pressure of 2.5 to 3.5 inchesof water, a heavy fraction could be separated from a light fraction. Theheavy fraction is enriched with endosperm and the light fractioncontains a mixture of germ and endosperm. After aspiration, the heavyfraction can be added directly to the starch fraction, and the lightfraction can be sieved using a U.S. standard sieve size of 6. Aftersieving, the +6 fraction contains primarily germ tissue and the −6fraction contains primarily endosperm tissue.

In all cases, the endosperm fractions or high starch fractions can becombined into a single fraction for fermentation to ethanol.

In another embodiment, the heavy fraction from the first aspiration,containing the germ and endosperm grits fractions, is sieved to separateout the fines and large grits from the intermediate fraction. This maybe accomplished utilizing U.S. standard sieve sizes of 20 and 10 in aSweco shaking screen. The +20-10 (intermediate) fraction can then bemilled, fracturing the endosperm into starch granules (fines) andforming the germ fraction into thin flakes. Milling may be done, forexample, in a Ferrell-Ross flaking roller mill. The fines, other largeendosperm pieces, and germ flakes are separated by sieving, aspiration,or other suitable method. The fines may then be combined with the finesand other high-starch composition fractions that were previouslyseparated from the pericarp and germ.

The separated germ flakes or whole germs may be processed in a number ofways. For example, they may be pressed in an expeller, or they may besubjected to an extraction. They may pressed by an expeller and thensubjected to an extraction. These processes will provide high-value cornoil.

In one embodiment, the fines and other high-starch composition fractionsare processed with a moisture source and by heat and enzymatic activityto provide a fermentation medium suitable for ethanol fermentation withSaccharomyces cerevisiae or another ethanol-producing microorganism. Afermentation medium is prepared, for example, by mixing the endospermfraction with a volume of water having a weight of two to three timesthe weight of the fines. This produces a slurry. Water may be obtainedfrom any source, but in typical embodiments it is fermentation backset,condensed evaporator water, or corn steep liquor. The temperature of theslurry is maintained at between 70 and 90° C. The pH of the slurry isadjusted to between to 5.2 and 6.0, typically 5.8. If the initial pH ofthe slurry is more acidic than the target pH, the pH may be adjusted,for example, by addition of sodium hydroxide or another base; if theslurry is initially too basic, its pH may be adjusted, for example, withaddition of sulfuric acid or another acid.

After the target slurry pH has been reached, the slurry is raised tobetween 82.2° C. and 93.3° C., preferably 87.8° C., and then held at theselected temperature for about 30 minutes. The slurry is then liquefiedwith addition of α-amylase enzyme and heated to 105-110° C. for 5 to 10minutes. In some embodiments, the slurry is heated to between 105 and110° C., preferably about 110° C. for between 5 and 15 minutes,preferably 10 minutes. The addition of the enzyme combined with heatingcauses breakdown of starch to maltooligosaccharides. The resultingslurry is then further treated by reduction of the temperature tobetween 60 and 75° C., preferably 70° C., addition of glucoamylase,adjustment of pH to about 4.5, and maintenance of the selectedtemperature for between 1 and 48 hours to saccharify themaltooligosaccharides to glucose monosaccharide. In a typical embodimentthe resulting slurry is used as a fermentation media for ethanolproduction with a fermentative microorganism.

The separated pericarp can be utilized as an animal feed. In analternative embodiment, treated pericarp as described below is added tothe media to increase the available saccharides for fermentation.Fermentation will typically include lowering the temperature of thefermentation mixture to between about 30 and 40° C., typically 35° C.,with addition of glucoamylase and at least one fermentativemicroorganism. A fermentative microorganism may be, for example, ayeast, bacteria, or fungus. Glucoamylase may be added at the doesrecommended by the manufacturer; typical dosages are 0.22 units ofglucoamylase/gram of starch. Other enzymes may also be added includinghemicellulases, proteases, cellulases, and feruloyl esterases to breakdown other soluble oligosaccharides to monosaccharides or to assist inthe enzymatic conversion of the oligosaccharides.

Fermentative ethanol is distilled, resulting in an ethanol stream and aremainder stream of yeast, gluten, water, non-starch fine fiber, andother non-soluble solids. The spent fermentation broth may be separatedinto a liquid fraction and a solids fraction, or the liquids may beevaporated to create or supplement a high solids animal feed. Inalternative embodiments the separation is performed by a press,centrifuge, filter, or evaporator. The separated solids may be used, forexample, as a wet animal feed. The separated liquids may be used, forexample, as process water or as a liquid animal feed.

B. Pericarp Processing

Embodiments of the invention provide various treatments and uses forpericarp. Typically, pericarp and fines are first separated from thetempered, milled corn, and the pericarp is subsequently separated fromthe fines. In one embodiment, the pericarp undergoes no furtherprocessing and is sold. For example, the pericarp may be sold as ananimal feed.

In a further embodiment, the pericarp is hydrolyzed a first time usingheat with the addition of acid. In this thermochemical hydrolysis, thepericarp is mixed with water and acid, then heated. Preferably water isadded until the pericarp/water mixture is at least 40% by weight, morepreferably 45% by weight. The pericarp/water ratio may be 60% pericarpto 40% pericarp. Sulfuric acid at a 1% concentration is the preferredacid for addition, but other acids that may be used include hydrochloricacid, nitric acid, peracetic acid, acetic acid, lactic acid, phosphoricacid, succinic acid, citric acid, and maleic acid. Sufficient acid isadded as needed for hydrolysis. The mixture is heated to between 145 and200 C, preferably 170° C., for between 0.1 and 60 minutes, preferably 11minutes. This thermochemical hydrolysis not only hydrolyzes celluloseand hemicellulose to produce a solubilized fraction enriched witholigosaccharides and monosaccharides such as xylose, (a slurry), butalso hydrolyzes most of the starch that is still attached to thepericarp tissue into oligosaccharides and glucose.

Following the initial hydrolysis, the hydrolyzed pericarp slurry may bewashed and pressed to provide a liquid solubilized fraction and a solidfraction. In the alternative, the slurry may be maintained as a mixture.

1. Separation of the Hydrolyzed Pericarp Slurry

If the hydrolyzed pericarp slurry is separated, the liquid fraction(containing hemicellulose and starch oligosaccharides) may be furtherhydrolyzed a second time to convert the oligosaccharides intomonosaccharides, particularly xylose and arabinose from the solubilizedhemicellulose, but also glucose from the solubilized cellulose andstarch. In an alternative embodiment, the liquid fraction is used toproduce chemicals. The chemical intermediates that may be produced fromthe oligosaccharides and monosaccharides include dehydrosugars, furans,levulinic acid, and formic acid. These chemicals may be used to producepolymers, fuel oxygenates, solvents, and many other chemicals.

If the liquid fraction of the hydrolyzed pericarp slurry is hydrolyzed asecond time, the second hydrolysis is conducted with the addition ofenzymes or other chemicals to facilitate the conversion ofoligosaccharides into monosaccharides. For example, the treatmentconditions may be 1% by weight sulfuric acid added to the hydrolysateand heated in a reactor to 121° C., 0.110 MPa for 30 minutes. For theenzymatic hydrolysis, the pH may be adjusted to pH 5-6 andhemicellulases, cellulases, feruloyl esterases, and proteases may beadded to the hydrolysate and the mixture may be held at 60° C. for 2 to48 hours. Amylase and glucoamylase may also be included to furthersolubilize starch derived oligosaccharides. The twice-hydrolyzed liquidfraction may be used as a stand-alone fermentation media, or it may beused to supplement a separate fermentation media. This includes, forexample, but is not limited to, an endosperm-derived media as describedin Section A herein.

The solids fraction of the hydrolyzed pericarp has a variety of uses.For example, it may be used as an animal feed, as a boiler feed, or as afeedstock for pyrolysis, biooil, gasification, or hydrothermalupgrading. Pyrolysis and hydrothermal upgrading each involve exposingthe solids to increased temperature and pressure for various times toliquefy the material, or at least a portion of the material. Theseliquefied materials can then be hyrdro-processed by the addition ofhydrogen gas over a catalyst to produce biooils. Tables 1 and 2 show thetypical conditions for pyrolysis and hydrothermal upgrading(liquefaction).

TABLE 1 Comparison of Liquefaction Process Operations hydrothermalPyrolysis liquefaction* operating temperature 450-500° C. 350° C.operating pressure 1 atm 200 atm residence time <1 sec 19 min oilproduct yield 70-75% wet bio-oil 50% dry oil oil product quality heatingvalue (HHV, 6886 Btu/lb 14200 Btu/lb Btu/lb) oxygen content 40% 15%water content 25% 5% viscosity@60° C. low (10 cps) high (17,000 cps)thermal stability No Yes distillable light ends and water half totwo-thirds only

TABLE 2 Further Hydroprocessing of Pyrolysis and HydrothermalLiquefaction materials hydrothermal Pyrolysis liquefaction operating lowtemp required typical (350-450° C.) temperature (250° C.) beforefinishing step (400° C.) catalysts Pd, Ru, Ni, CoMo, NiMo typical (NiMoor CoMo) liquid hourly space 0.1 0.19 velocity product gasoline 0.3liter/liter feed 0.8 liter/liter feed yield oil product quality gasolineand diesel range gasoline and diesel range hydrocarbons hydrocarbonsoxygen content 1.3 0.1 H/C ratio 1.6 1.5 water content 500 ppm very low

2. Utilization of Hydrolyzed Pericarp in a Mixture

If the hydrolyzed pericarp is not separated, then the combined liquidand solid fractions may be treated with enzymes to hydrolyze the mixturea second time to partially or completely hydrolyze the solids tooligosaccharides and monosaccharides and partially or completely convertsoluble oligosaccharides to monosaccharides. Suitable enzymes andaccessory enzymes include, for example, but are not limited toproteases, cellulases, hemicellulases, feruloyl esterases, andstarch-degrading enzymes. The enzyme hydrolysis may occur, for example,at 60° C. for 2 to 72 hours. The twice-hydrolyzed slurry may then beused as a fermentation media for ethanol or other chemicals. It may alsobe used to supplement a fermentation media as described in Section Aherein. In the alternative, the twice-hydrolyzed slurry may be used toproduce animal feed, boiler feed. After fermentation, any residualcarbohydrates in the monosaccharide, oligosaccharide or polysaccharideform may be used as an animal feed or for pyrolysis, biooil production,gasification, or hydrothermal treatment.

EXAMPLES

The examples below are only representative of some aspects of theinvention. These examples should not be interpreted as limiting theinvention in any way not explicitly stated in the claims.

Example 1

Corn milling tests have been conducted on dry fractionation of cornkernels at ADM. This run consisted of placing 5 kg of corn kernels in arotating sealed vessel and adding 10% water. The vessel was rotated for1 hour at room temperature and then the kernels were removed. Thetempered corn kernels were roughly ground through a Fitz Comminutorfitted with a ¼″ screen; followed by aspiration through a Kice aspiratorwith a 1 inch of water differential; the “overs” and “throughs” from theaspirator were sieved in a Sweco shaking screener at 6, 12, and 20 meshsizes. After sieving, the intermediate particles (−6/+20) from the“throughs” were roller milled twice at a gap setting of 1.1 on theFerrell-Ross Flaking roller mill and then sieved in a Sweco shakingscreener at 6 and 12 mesh sizes. The fines (20 mesh or below, −20) werecombined prior to analysis. This produced 6 fractions as shown in Table1 below. With the exception of the pericarp and the germ, the remaininglisted components form the endosperm.

The results show that the fines are highly enriched in starch ascompared to the native kernels, and depleted of NDF (neutral detergentfiber, equivalent to hemicellulose, cellulose and lignin), fat andprotein. This fines fraction is the largest fraction at 35.6%. Othersamples enriched in starch include the Grits (33.6% of the yield) andRolled Fines (10.1% of the yield). These fractions are also enriched inprotein and depleted in NDF. The Rolled Pieces and the Grits fractionsare compositionally the most similar to the overall corn kernelcomposition.

The pericarp fraction can be hydrolyzed by mixing the pericarp withwater (or optionally, backset, corn steep liquor or other process water)until the moisture level is 40-60%. The pericarp slurry can then beplaced into a pressurized reactor and 1 wt/wt % sulfuric acid added. Thereactor can be heated by direct or indirect steam heating, or byelectrical heating. The reactor is heated to 120 to 200° C. for 1 to 120minutes, preferably to 150-175° C. for 11 to 30 minutes. The pressure inthe reactor will be from approximately 2 bars at 120° C. toapproximately 16 bars at 200° C.

After the initial hydrolysis has occurred, the hydrolyzed pericarpslurry is optionally mixed with an additional water source, which couldinclude corn steep liquor, backset, water or process water. The slurryis cooled to approximately 60° C. and enzymes such as hemicellulases,cellulases, proteases, and feruloyl esterases are added to hydrolyze thehydrolyzed solids and soluble oligosaccharides. The slurry can then beadded to the fermentation media prepared from the starch enrichedfraction.

TABLE 1 10% Moisture Tempered Corn - Fractions Compositions (%) YieldProtein Ash Fat NDF* Starch Corn Kernels 7.42 1.3 3.94 10.8 71.38 Fines35.60 6.16 0.60 2.18 2.90 87.15 Grits 33.60 9.39 1.10 4.21 5.06 76.95Rolled Fines 10.10 7.97 0.64 2.74 3.45 83.85 Germ 2.70 16.50 6.29 19.4717.45 33.59 Pericarp 10.00 8.78 1.68 3.97 43.30 36.57 Rolled Pieces 8.0012.10 2.97 8.54 9.02 64.07

The resulting products from this processing yield products as shown inTable 2, below. Table 2 compares the expected product yield of untreatedcorn with corn treated as described in this example. Treated cornincreased ethanol production (2.976 gal/bu, compared to 2.700 gal/bu),increased yield of biodiesel, and increased boiler energy production.Production of animal feed is decreased by about 9 pounds/bu, but theother beneficial products and uses have a greater value (particularlyfor supplying energy) and are therefore more desirable. The animal feedthat is produced may be used for many species, including ruminants.

TABLE 2 Product Yields Ethanol, Boiler Energy, Animal gal/bu Btu/bu(7300 Btu/lb) Feed, lb/bu Biodiesel, lb/bu Corn 2.700 17 Biodiesel,kg/bu Endosperm 2.812 7.18 Germ 0.227 0.77 Pericarp/Hull 0.264 17,520

Example 2

Example 2 describes the separation and utilization of the liquids andsolids from the hydrolyzed pericarp stream. After the sulfuric acidhydrolysis of the pericarp fraction as described in Example 1, thehydrolyzed pericarp slurry is processed using a screw press orcentrifuge to separate the solids and liquid. For example a Vincentscrew press model CP-4 could be utilized to separate the solids andliquids. The solids can be washed in the press or centrifuge also toremove more soluble oligosaccharides and monosaccharides from theremaining hydrolyzed solids.

The separated liquid from the hydrolyzed pericarp slurry can behydrolyzed again with an additional acid hydrolysis or with an enzymehydrolysis. This will break down the soluble starch and hemicelluloseoligosaccharides to monosaccharides that can be fermented to ethanol orother chemicals. The conditions for the acid hydrolysis are 121° C.(approximately 2 bar) for 30 minutes. The conditions for the enzymehydrolysis are 60° C. for 1 hour using starch hydrolyzing enzymes,hemicellulases, and feruloyl esterases.

The separated solids may be optionally dried and pelletized and sold asan animal feed. Or optionally, the separated solids may be heated in areactor at various conditions to either pyrolyze, thermochemicallytreat, hydrothermally treat, or gasify the solids. These conditions willproduce oils and gases that can be utilized as fuels and chemicals.

Example 3

Example 3 reports an additional embodiment of the invention, the flowchart for which may be viewed as FIG. 6. The corn was tempered for 15 to60 minutes and milled as described in Example 1 above. Then the groundcorn was aspirated in a Kice aspirator at a differential pressure of0.75 inches of water. The light fraction or overs were sieved in a Swecoshaking screener using a U.S. standard sieve size of 12. The +12fraction consists of the pericarp fraction (Fiber Fraction, Product 1,in FIG. 6) and the −12 fraction consists of an endosperm fraction(Starch Fraction, Product 2, in FIG. 6).

The heavys or throughs were then aspirated again at 2.9 inches of waterand the heavy fraction was an endosperm fraction (Starch Fraction,Product 3, in FIG. 6). The lights were sieved in a Sweco sieving screenusing U.S. standard sieve sizes of 6 and 10. The +6 fraction was thegerm fraction (Germ Fraction, Product 6, in FIG. 6), and the other twofractions were endosperm fractions (Starch Fraction, Product 4, andStarch Fraction, Product 5, both in FIG. 6).

Product analysis for this embodiment is shown in Table 3.

TABLE 3 Product Analysis for Example 3 % of Total Product Run NumberProduct Number (as-is) 1 1 11.3 2 27.3 3 11.5 4 22.0 5 25.1 6 2.8 2 110.6 2 26.6 3 10.8 4 23.4 5 25.6 6 3.0 3 1 11.6 2 26.1 3 11.6 4 22.8 524.8 6 3.3 4 1 9.5 2 27.9 3 11.5 4 23.6 5 24.6 6 3.0

Patents, patent applications, publications, scientific articles, books,web sites, and other documents and materials referenced or mentionedherein are indicative of the levels of skill of those skilled in the artto which the inventions pertain, as of the date each publication waswritten, and all are incorporated by reference as if fully rewrittenherein. Inclusion of a document in this specification is not anadmission that the document represents prior invention or is prior artfor any purpose.

The terms and expressions employed herein have been used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions, or any portions thereof, to exclude anyequivalents now know or later developed, whether or not such equivalentsare set forth or shown or described herein or whether or not suchequivalents are viewed as predictable, but it is recognized that variousmodifications are within the scope of the invention claimed, whether ornot those claims issued with or without alteration or amendment for anyreason. Thus, it shall be understood that, although the presentinvention has been specifically disclosed by preferred embodiments andoptional features, modifications and variations of the inventionsembodied therein or herein disclosed can be resorted to by those skilledin the art, and such modifications and variations are considered to bewithin the scope of the inventions disclosed and claimed herein.

Specific methods and compositions described herein are representative ofpreferred embodiments and are exemplary and not intended as limitationson the scope of the invention. Other objects, aspects, and embodimentswill occur to those skilled in the art upon consideration of thisspecification, and are encompassed within the spirit of the invention asdefined by the scope of the claims. Where examples are given, thedescription shall be construed to include but not to be limited to onlythose examples.

It will be readily apparent to one skilled in the art that varyingsubstitutions and modifications may be made to the invention disclosedherein without departing from the scope and spirit of the invention, andfrom the description of the inventions, including those illustrativelyset forth herein, it is manifest that various modifications andequivalents can be used to implement the concepts of the presentinvention without departing from its scope. A person of ordinary skillin the art will recognize that changes can be made in form and detailwithout departing from the spirit and the scope of the invention. Thedescribed embodiments are to be considered in all respects asillustrative and not restrictive. Thus, for example, additionalembodiments are within the scope of the invention and within thefollowing claims.

1. A modified process for ethanol production from a grain, comprising:in a dry-grind grain processing plant, separating a pericarp enrichedfraction from germ and endosperm enriched fractions of a ground grain;hydrolyzing cellulose and hemicellulose from the separated pericarpfraction to form a xylose enriched soluble fraction; adding the xyloseenriched soluble fraction to a fermentation medium comprising hydrolyzedstarch from the endosperm enriched fraction of the grain; and fermentingthe medium to produce ethanol.
 2. The process of claim 1 wherein thehydrolyzing includes thermochemically treating the separated pericarpfraction by exposure to a temperature greater than 25° C. in thepresence of at least one of a mineral acid, an organic acid, a mineralbase, and an oxidizing agent.
 3. The process of claim 2 wherein thehydrolyzing further includes treating the separated pericarp fraction toat least one of a cellulose and a hemicellulose degrading enzyme.
 4. Theprocess of claim 1 wherein the pericarp enriched fraction is obtained byaspirating the ground grain by upward flow of gas at a first airpressure in a hopper and harvesting a first fraction of lightercomponents that are enriched toward an upper portion of the hopper beingseparated from to a first fraction of heavier components that areenriched in a lower portion of the hopper.
 5. The process of claim 4wherein after harvesting the lighter components, the aspirating gas isincreased to a second air pressure greater than the first air pressureto separate the first fraction of heavier components into a secondlighter fraction enriched with endosperm and a second heavier fractionenriched with germ, and; harvesting the germ enriched fraction and theendosperm enriched fraction.
 6. The method of claim 5 wherein theendosperm enriched fraction is liquefied and treated with a starchhydrolyzing agent to provide the hydrolyzed starch for the fermentationmedium.
 7. The method of claim 5 wherein oil is extracted from the germenriched fraction.
 8. The method of claim 1 wherein the xylose enrichedsolubilized fraction is separated from non soluble pericarp material andthe non-soluble pericarp material is further treated to at least oneprocess selected from pyrolysis and hydrothermal upgrading.
 9. Theprocess of claim 1 wherein separating the pericarp enriched fractionfrom the germ and endosperm enriched fractions includes moistening thedry grain by adding about 10% wt of water per wt of dry grain andtempering the moistened grain by incubating at 20-40° C. for a period ofat least 15 minutes.
 10. A modified process for ethanol production,comprising: in a dry grind grain processing plant, tempering a dryweight of grain by adding about 10% wt of water per dry weight of grainand heating to a temperature of about 20-40° C. for a period sufficientto swell a germ component of the grain; grinding the tempered grain;separating the ground grain by aspiration to obtain a first fractionenriched with pericarp and a first amount of starch fines and a secondfraction enriched with endosperm and germ; separating the first fractionby sizing to form a pericarp enriched fraction and a fines enrichedfraction; separating the second fraction into an endosperm enrichedfraction and a germ enriched fraction; adding water and a hydrolyticagent to the pericarp enriched fraction to form a first mixture andheating the first mixture for a time and temperature sufficient tohydrolyze at least 45% of the fiber in the pericarp into a soluble sugarfraction containing xylose.
 11. A method for fractionation of a cornstream into endosperm, germ, and pericarp fractions, comprising: a.tempering a corn stream; b. aspirating said tempered corn stream at afirst differential pressure, thereby producing at least a first lightfraction and a first heavy fraction; c. separating said first lightfraction into at least a pericarp fraction and a first endospermfraction; d. aspirating said first heavy fraction at a seconddifferential pressure, thereby producing at least a second endospermfraction and a second light fraction; and e. separating said secondlight fraction into at least a third endosperm fraction and a germfraction.
 12. The method of claim 11, wherein said second differentialpressure is greater than said first differential pressure.
 13. A methodfor fermentative production of ethanol from corn, comprising: a.fractionating corn according to the method of claim 11; b. providing afermentation media comprising said pericarp fraction, said firstendosperm fraction, said second endosperm fraction, and said thirdendosperm fraction; and c. fermenting said fermentation media, therebyproducing ethanol.
 14. The method of claim 13, wherein the yield ofethanol per bushel of corn is between about 2.7 to about 3.0 gallons perbushel of corn.
 15. A method for providing a hydrolyzed pericarp fuel,comprising: a. fractionating corn according to the method of claim 11;b. hydrolyzing said pericarp fraction, thereby producing a hydrolyzedpericarp fuel.
 16. The method of claim 15, further comprising separatingsaid hydrolyzed pericarp into a liquid stream and a solid fraction,wherein said solid fraction is a hydrolyzed pericarp fuel.
 17. A methodfor fractionating corn into germ, endosperm, and pericarp fractions,comprising: a. tempering a corn stream; b. grinding the tempered cornstream to provide a mixture comprising pericarp, fines, germ, andendosperm; c. aspirating said mixture to produce a fraction comprisingpericarp and starch fines and a fraction comprising germ and endosperm;d. separating said fraction comprising pericarp and starch fines toprovide a pericarp fraction and a first starch fines fraction; e.separating said fraction comprising germ and endosperm to provide asecond starch fines fraction and a germ fraction; and f. combining saidfirst starch fines fraction and said second starch fines fraction toproduce an endosperm fraction.
 18. The method of claim 17, wherein saidfraction comprising germ and endosperm is separated by at least onemethod selected from the group consisting of aspiration and sieving. 19.A method for providing ethanol and stillage from a whole corn stream,comprising: a. tempering a whole corn stream by adding 10% water byweight and holding for 15 minutes to one hour at about 25° C., producinga tempered corn stream; b. grinding said tempered corn stream to producea ground corn stream mixture comprising pericarp, fines, germ andendosperm; c. aspirating said ground corn stream mixture to produce apericarp and fines fraction and an endosperm and germ fraction; d.screening said pericarp and fines fraction to produce a pericarpfraction and a first fines fraction; e. hydrolyzing said pericarpfraction by adding water to increase the total weight to at least 1.67times the starting weight of said pericarp fraction and adding an acidas needed, and heating to between about 150 to 170° C. for about 11 to30 minutes; f. hydrolyzing the pericarp fraction of step (e) by addingenzymes to said pericarp fraction; g. milling said endosperm and germfraction to provide a second fines fraction and germ flakes; h.screening said germ flakes and said second fines fraction to separatesaid germ flakes and said second fines fraction; i. combining said firstfines fraction and said second fines fraction to provide a combinedfines fraction; j. mixing said combined fines fraction with 2 to 4 timesby weight of water to produce a slurry, adjusting pH of the slurry to5.8, and heating to 87.8° C. for 30 minutes; k. heating the mixture ofstep (j) to 110° C. for ten minutes with addition of α-amylase at a doseof 10-20 units/gram of starch; l. cooling the mixture of step (k) to 70°C., adding α-amylase at a dose of 10-20 units/gram of starch, andholding at 70° C. for 60-120 minutes; m. combining a hydrolyzed pericarpfraction with the product of step (l) to provide a fermentation media;n. lowering the temperature of the fermentation media of step (m) to 35°C., adding glucoamylase at a dose of 0.22 units/gram of starch orGLU/gram), and fermenting for 48-64 hours to produce ethanol andstillage.
 20. The method of claim 19, further including separating thehydrolyzed pericarp of step (f) into a solid fraction and a liquidstream prior to combining the hydrolyzed pericarp fraction with thefermentation media of step (l), and combining only the liquid streamwith the product of step (l).